Multibladed disk knife slitting mechanism



Dec. 15, 1953 H. A. BURDwooD MULTIBLADED DISK KNIFE SLITTING MECHANISM Filed Dec. lO, 1947 Patented Dec. l5, V195.3

MULTIBLADED DISK KNIFE SLITTING MECHANISM Howard A. Burdwood, Portland, Maine Application December 10, 1947, Serial No. 790,765

1 Claim. l

This invention relates to a machine for slitting sheet material so as to form simultaneously a plurality of narrow strips, such strips being preferably of uniform Width.

It is an object of the invention to provide a machine for cutting cloth, paper, leather, or other equivalent sheet materials into strips for any desired purpose. For example, pieces of cloth are frequently cut into strips for the manufacture of hooked, crocheted or braided rugs. Cutting narrow strips from pieces of cloth by the use of ordinary scissors is slow and tedious and usually results in strips of more or less irregular width. According to the present invention, a slitting mechanism is provided which slits the marginal portion of a sheet into a plurality of narrow strips. This mechanism is characterized by a rotary cutter having a plurality of disk blades which are coaxial and are uniformly spaced apart. A press roll is pressed tangentially against the blades, the press roll being pivotally supported by a floating connection so that its pressure against the individual blades is equalized. A work table is also provided in conjunction with a knife and press roll.

The mechanism embodied in the invention is designed for economy, efficiency and ease of assembly and adjustment.

Further advantageous features of the invention will be apparent from the following description thereof and from the drawing, of which:

Figure 1 is an elevational view of a mechanism embodying the invention;

Figure 2 is a section on line 2-2 of Figure l; and

Figure 3 is a rear elevational view of the mechanism shown in Figure 1.

The slitting mechanism illustrated on the drawing comprises a main frame I0, which includes a downwardly-extending bracket I2 having a clamp screw I4 threaded through the extremity thereof so as to facilitate the clamping of the machine on an ordinary table I6. Mounted on the frame I is a work table 20 which has a rectangular aperture 22. A rotary knife 24 is rotatably mounted beneath the table so that its top projects up through the aperture 22. This knife is mounted on a horizontal shaft 26 which is journaled in the frame I0 and is provided with an operating crank 28, having a crank handle (not shown) at its extremity. The knife 24 is mounted on a portion 30 of the shaft 26 of reduced diameter, being clamped in place by a wing nut 32 threaded on a reduced extension 2 34 of the shaft. A suitable washer 36 may be employed between the nut and the knife 24.

As indicated in Figure 2, the knife preferably consists of a plurality of, annular disk blades 45 with sharp Acircumferential edges arranged in coaxial, equally spaced relation. These blades are embedded in and secured together by a hub member 42 of suitable cast metal. This hub member 42 is cylindrical and is coaxial with the blades 4i). The outside diameter of the hub member is necessarily less than that of the blades, the difference being suiiicient to accommodate the thickness of the sheet material to be slitted, but the hub diameter is preferablyr as great as is practical so as to fill the aperture 22 in the work table 20 and thus to minimize the possibility of the strips of material becoming tangled and jammed at the knife. The hub member 42 has an axial bore adapted to receive the reduced portion 30 of the shaft 26 with a close fit so that there is lpractically no lateral play between the knife 24 and the shaft on which it is mounted. Since the cast metal 42 may have a co-eicient of thermal expansion different from that of the blades, the Ablades are preferably made with vcircular grooves 44 in one or both faces. The inner diameter of the annular `blades is preferably greater than the diameter of the bore of the hub member 42, so that except for the projecting circumferential portion of each blade, the entire blade surface is covered by the cast metal. When the hub member is cast so as to embrace the blades 40, the metal enters the grooves 44 and thus locks the several blades against any looseness with respect to the hub member.

A cylindrical press roll 50 is supported above the knife 24 and is adapted to press firmly against the cutting edges of the blades 49. This roll is rotatably mounted on a shaft 52 which extends between the arms 54 of a fork 56. The shank 58 of the fork is curved to support a shaft 60 which extends approximately parallel to the arms 54. The shaft 66 extends through and bears in the end portion 62 of an arm 64 which projects laterally from a bracket 66. Preferably, both end portions of the shaft 60 are secured in the fork 56, the shaft providing a pivotal or floating connection between the roll 50 and the bracket 66. The axis of the shaft 60 is at right angles to a plane containing the axis of rotation of the roll 50. Hence, the axis of this roll can rock freely so as to equalize the pressure of the roll against the individual blades 40. The roll 50 is pressed firmly against the blades 40 by any suitable means such as a tension rod 10, one end of which is anchored in the main frame l0, as at 12, the other end being screw-threaded to receive a wing nut 14. The portion of the rod 10 adjacent to the wing nut passes through the bracket 66 near the extremity thereof where the arm 64 projects laterally therefrom. The bracket `66 is pivotally mountedf on theframe l0, as at 16.1, By screw.- ing down the nut 14,' the pressurerof the roll 50 against the blades 40 can be adjustably varied. If the nut 14 is removed from the rod` 10, the bracket 66, with the roll ;,5.IJ1 and-cone` necting members, `can be swung back out oft-thee way of the knife 24 to facilitate the clearing of any jammed material or replacement oftheknife.

Along the side edge of the table 20 adjacent to the aperture 22 is a guide rail 80 whichmay be secured to the table-by a bolt 82 and wing nut 84;; This` guidefraili.canA thus beadjuted so thev portion remote. from4 theffend=,fsecuredby thev "bolt 82 is .moved toward vor; fromsthe' nearest lblade 40, thusdetermining.- the Width;ofthe marginalstrip out from--the/,work` sheet-which is sent through the:-slitter. This width is-.pref, erably thesameias that :of thefstripsfcut between successive blades;l If; widen or. narrower stri-ps are desired, another -rotaryknifewith differently spacedblades lis substitutedyfor the knife 24;-

and the guide 80 .isadjustedaccordingly.

For convenienceand economy` in manufacture slitting mechanismsf` i, the mainfA frame; l A andv bracket EB maybefdieecastingspf, afsu-itablemetal alloy having sufficient .mechanical strer,1gtl1.` For example, an alloy ycorrtain-ing ,96% zinc and about. 4%; aluminumissuitable, for` thesevparts.'v A, lsimilarV alloy can .-,beausredf inl i casting; the fshaft. 26 and crank28 in-one pieceeaboutfagsteel core which prOjeCtsatfthesendf ofgtlne` shaft andwis, screw-threaded` at 1 34:; Afsimilar; alloy; cani. be used for the` hub membexMZ .lof .thei rotaryv` knife, 24, the-blades beinggof thigh-speed?? steel;A tempered.- andr ground .before beingfassembled. A suitable examplerof highzspeed steelisfa ysteel containing. 18%', tungsten, 4% .chromium;, 1%v vanadium and;.75.%; carbon; but otherhighspeedi steels, .suchf as those.:A containing; molybdenum; with' or instead of: tungsten, are alsosatisfactory for the.purpose.v The'melti-ng pointlofthe. alf; loy is notfhigh Aenoughfto soften oeotherwiseaf: feet theA blades adverselywhengthe; hubgmemf ber is Acast,\1v-itha.set of` bladesfthereing The press roll is` preferably ofarzhardenedfgcarborr steel which is not scored by the cutting edges of the blades when pressed against them. It is to be understood, however, that the foregoing materials are referred to by way of illustration and. that invention is not necessarily limited thereto.

What I claim is:

A slitting mechanism comprising a frame, a horizontal Iwork table with, any;v aperture secured on said frame,- a-multi-bladed disc-knife mounted below said table for rotation about a horizontal axis, said knife projecting up through said... aperture slightly above the level of the table, a rotatable shaft journalled in said frame and carrying said knife, an operating crank in saidshaft; a. .bracket pivotally secured at one en d to said frame at one side of said shaft and extending above and beyond said shaft to the ottici-.iside thereof, a tension member attached at one end to said frame on said other side of the shaft. and,adjustably attached tothe free endof the bracket, anf armjprojecting from said bracket out over thetab'le, a press roll*` supported on said knife andY rotatable aboutan axis parallel to that of the knife, supporting means operatively connecting. said press roll and arm whereby rocking movement of said bracket about its pivot moves said press roll to or from contact with -said knife, and means on said tension member operable to, draw thefree end of said bracket. downward so asto Vary the pressure yo1' said press roll against said knife.

HOWARD A; BURDWOOD.-

References Cited -vin the le of this'patent UNITEDSTIATES PATENTS.

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